The present invention relates to a simulation and security device for a data entry keyboard of a computer. It applies to the transmission of call instructions to a computer from a data entry keyboard. It makes it possible particularly to prevent any operator working on this keyboard from using the computer with a program other than the one on which this computer must operate.
It is known that a computer operates from a working program recorded in a memory. This working program can be executed only after the computer has been initialized. This initialization program is generally recorded in a read-only memory (ROM memory) and the working program is executed when, after the initialization, call instructions, specific to the program in question, are transmitted to the computer through an operator acting on the data entry keyboard of this computer. The working program, which is generally contained in a random-access memory, therefore cannot be executed unless the call instructions of this program have been correctly given through the keyboard. If an operator transmits instructions different from those which are necessary for the execution of the program, this operator can then work on a program different from the one which was intended to be used by the operator. This happens frequently, especially when the computers are used for education. Indeed, it often happens that, in this type of application, the students introduce, after initialization, instructions which do not correspond at all to the call instructions of the program; these students then work on a program of their choice which does not at all correspond to the program intended for the desired teaching.